eZ80L92 MCU
Product Specification
199
Table 125. Recommended Crystal Oscillator Specifications (20 MHz Operation)
Parameter
Frequency
Resonance
Mode
Series Resistance (R
S
)
Load Capacitance (C
L
)
Shunt Capacitance (C
0
)
Drive Level
Value
20
Parallel
Fundamental
25
20
7
1
Ω
pF
pF
mW
Maximum
Maximum
Maximum
Maximum
Units
MHz
Comments
32 KHz Real-Time Clock Crystal Oscillator Operation
oscillator with an external 32 KHz, fundamental-mode, parallel-resonant crystal. The rec-
ommended crystal specifications are provided in Table 126. A printed circuit board layout
should add no more than 4 pF of stray capacitance to either the RTC_X
IN
or RTC_X
OUT
pins. If oscillation does not occur, reduce the values of capacitors C
1
and C
2
to decrease
loading.
An on-chip MOS resistor sets the crystal drive current limit. This configuration does not
require an external bias resistor across the crystal. An on-chip MOS resistor provides the
biasing.
On-Chip Oscillator
RTC_X
IN
RTC_X
OUT
32 kHz Crystal
(Fundamental Mode)
R
1
= 220 Ω
C
2
= 18 pF
C
2
= 18 pF
Figure 45. Recommended Crystal Oscillator Configuration (32KHz operation)
PS013012-1004
PRELIMINARY
On-Chip Oscillators
ZILOG [ ZILOG, INC. ]
